Our tour of the eight new stations on the $8.3 billion North West Rail Link — which you can follow here online every week — takes us back to Cherrybrook station where the first section of concrete will be poured into the station box tomorrow, taking about 24 hours to dry.

Since the $1.15billion tunnelling contract was awarded just over a year ago, there’s been a total transformation at the site on Castle Hill Road from undulating slopes to a construction zone with workers’ sheds and a massive ‘‘box’’ in the ground, supported using rock bolts, anchor supports and concrete.

A Transport for NSW spokesman told the News that at 14 metres, excavation of this station box had reached tunnelling depth and would form the base of Cherrybrook station.

He said the box was ‘‘almost ready’’ for the two massive tunnel boring machines (TBMs) which will start their work on Australia’s longest railway tunnels.

‘‘The two Cherrybrook TBMs will dig six kilometres to Epping, while the two other two TBMs will arrive here after digging nine kilometres from Bella Vista,’’ he said.

‘‘Once tunnelling is complete, we’ll be getting on with building the platforms and railway station in this box area, laying the new tracks and delivering other benefits like the 400 commuter car parking spaces.’’

Also completed is a night-time storage shed for the concrete segments which will line the twin 15-kilometre tunnels.

A TfNSW spokesman said 100,000 of these concrete segments would be required to make 16,000 concrete rings, which will form the inside of the tunnels.

The night storage shed, where crushed rock from the tunnels will be stored, is almost complete as well.

In coming months conveyors for the crushed rock coming out of the tunnels, a water treatment plant, a grout plant for the concrete tunnel lining and a mechanical workshop will be built.

■ 65,000-plus tonnes of crushed rock removed during excavation of the station box area;

■ About 24,000 tonnes of concrete poured on-site to date;

■ More than 25kilometres of thick steel wires drilled into the ground for support;

■ Noise barriers installed;

■ Construction of internal sealed roads and a retaining wall along Castle Hill Road; and